ETrade  must be really hurting from recent events in the financial sector. First, they have one of the highest 6-month CD rates out there with a mere $1000 minimum (it’s 5.10% at last check) and now they’re letting their account holders trade absolutely free  for one day, Wednesday December 19th.
Here are the terms and conditions of the ETrade free trade offer (there are more on that page but these are the basics):
Unlimited commission-free trade offer is valid for trades entered by E*TRADE Securities customers in U.S. stocks, options and futures from 8:30 PM EST on 12/18/07 to 8:30 PM EST on 12/19/07. Unlimited commission-free trade offer is valid for trades entered by E*TRADE Securities customers in non-U.S. stocks from 5:30 PM EST on 12/18/07 to 5:30 PM EST on 12/19/07. This offer does not include commissions on trades in mutual funds or fixed income securities, but does apply to options contract fees.
So, if you are using ETrade, use this as a chance to clean up your portfolio (do some rebalancing, take advantage of the wash rule, whatever) without paying commissions.